Abstract
Elevated levels of both ozone and UV‐B radiation are typical for high‐altitude sites. Few studies have investigated their possible interaction on plants. This study reports interactive effects of O 3 and UV‐B radiation in four‐year‐old Norway spruce and Scots pine trees. The trees were cultivated in controlled environmental facilities under simulated climatic conditions recorded on Mt Wank, an Alpine mountain in Bavaria, and were exposed for one growing season to simulated ambient or twice‐ambient ozone regimes at either near ambient or near zero UV‐B radiation levels. Chlorotic mottling and yellowing of current year needles became obvious under twice‐ambient O 3 in both species at the onset of a high ozone episode in July. Development of chlorotic mottling in relation to accumulated ozone concentrations over a threshold of 40 nL L –1 was more pronounced with near zero rather than ambient UV‐B radiation levels. In Norway spruce, photosynthetic parameters at ambient CO 2 concentration, measured at the end of the experiment, were reduced in trees cultivated under twice‐ambient O 3 , irrespective of the UV‐B treatment. Effects on photosynthetic capacity and carboxylation efficiency were restricted to trees exposed to near zero levels of UV‐B radiation, and twice‐ambient O 3 . The data indicate that UV‐B radiation, applied together with O 3 , ameliorates the detrimental effects of O 3 . The data also demonstrate that foliar symptoms develop more rapidly in Scots pine than in Norway spruce at higher accumulated ozone concentrations. Symbols and abbreviations: LSD, least significant difference; PAS300, UV‐B irradiance weighted according to the plant action spectrum of Green et al . (1974) normalized at 300 (nm); AOT40, (AOT = accumulated over threshold) reflects the sum of hourly ozone concentrations above 40 nL L –1 during daylight hours (> 50 Wm –2 ) ( Kärenlampi & Skärby 1996 ); A 350 , net photosynthesis at ambient CO 2 ; G 350 , stomatal conductance for water vapour at ambient CO 2 ; A 2500 , net photosynthesis at saturating CO 2 (maximal potential photosynthetic activity); CE, carboxylation efficiency; ROS, reactive oxygen species; RuBP, ribulose 1,5‐bisphosphate; Rubisco, ribulose 1,5‐bisphosphate carboxylase/oxygenase; GLM, general linear model.
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Claims 6
Claim · model-written summary
Twice ambient ozone caused chlorotic mottling and yellowing of current year needles in Norway spruce.
- Taxon
- Norway spruce
Picea abiest0 - Treatment
- twice‐ambient O 3e0
- Outcome
- Chlorotic mottling and yellowing of current year needlese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chlorotic mottling and yellowing of current year needles became obvious under twice‐ambient O 3 in both species”
t0“Norway spruce”
Claim · model-written summary
Twice ambient ozone caused chlorotic mottling and yellowing of current year needles in Scots pine.
- Taxon
- Scots pine
Pinus sylvestrist0 - Treatment
- twice‐ambient O 3e0
- Outcome
- Chlorotic mottling and yellowing of current year needlese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chlorotic mottling and yellowing of current year needles became obvious under twice‐ambient O 3 in both species”
t0“Scots pine”
Claim · model-written summary
Chlorotic mottling was more pronounced at near zero UV-B than ambient UV-B.
- Taxon
- Norway spruce and Scots pinePicea abiesPinus sylvestrist0
- Treatment
- near zeroe0
- Outcome
- Development of chlorotic mottlinge0
- Direction
- more pronouncede0
- Qualifier
- over a threshold of 40 nL L –1e0
- Comparator
- ambient UV‐B radiation levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Development of chlorotic mottling in relation to accumulated ozone concentrations over a threshold of 40 nL L –1 was more pronounced with near zero rather than ambient UV‐B radiation levels”
t0“Norway spruce and Scots pine”
Claim · model-written summary
Twice ambient ozone reduced photosynthetic parameters in Norway spruce regardless of UV-B treatment.
- Taxon
- Norway sprucePicea abiese0
- Treatment
- twice‐ambient O 3e0
- Outcome
- photosynthetic parameterse0
- Direction
- reducede0
- Qualifier
- irrespective of the UV‐B treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In Norway spruce, photosynthetic parameters at ambient CO 2 concentration, measured at the end of the experiment, were reduced in trees cultivated under twice‐ambient O 3 , irrespective of the UV‐B treatment”
Claim · model-written summary
Effects on photosynthetic capacity and carboxylation efficiency occurred only under near zero UV-B with twice ambient ozone.
- Taxon
- Norway sprucePicea abiest0
- Outcome
- photosynthetic capacity and carboxylation efficiencye0
- Qualifier
- near zero levels of UV‐B radiation, and twice‐ambient O 3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Effects on photosynthetic capacity and carboxylation efficiency were restricted to trees exposed to near zero levels of UV‐B radiation, and twice‐ambient O 3”
t0“Norway spruce”
Claim · model-written summary
Foliar symptoms developed faster in Scots pine than Norway spruce at higher accumulated ozone concentrations.
- Taxon
- Scots pinePinus sylvestrise0
- Outcome
- foliar symptomse0
- Direction
- more rapidlye0
- Qualifier
- higher accumulated ozone concentrationse0
- Comparator
- Norway sprucee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“foliar symptoms develop more rapidly in Scots pine than in Norway spruce at higher accumulated ozone concentrations”
The same questions in other papers
ozone · physiology: photosynthesis · Picea abies (Norway spruce)Results differ
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- positive
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See all 10 papers →ozone · disease · Pinus sylvestris (Scots pine)Results agree
4 papers in the same direction as this paper
- negative
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- no effect
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See all 5 papers →ozone · disease · Picea abies (Norway spruce)Results agree
4 papers in the same direction as this paper
- negative
- negative
- negative
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See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.